1. Field of the Invention
This invention relates to a method of manufacturing a substrate for mounting electronic components.
2. Description of the Prior Art
A conventional example of a substrate for mounting electronic components which has a lead frame for electrically connecting the electronic component externally is shown in FIG. 1. An electronic component mounting section 10 of a conventional substrate for mounting electronic components shown in FIG. 1 is formed separately from a lead frame 1. In other words, the electronic component mounting section 10 is formed by preparing as a base material a glass epoxy copper-covered laminated board, a glass triazine copper-covered laminated board, glass polyimide copper-covered laminated board or the like, and forming it by a normal subtractive method through the steps of perforating, through-hole plating, etching, etc. The electronic component mounting section is bonded to the lead frame by a adhesive sheet or its equivalent, and the electronic component mounting section is electrically connected to the lead frame only by fine wiring 9 made of gold or the like having weak mechanical strength.
Since the electronic component mounting section is electrically connected to the lead frame only by fine metal wiring made of gold or the like in the prior art as described above, it has a very weak structure against external mechanical stress. In other words, the connecting reliability of the electronic component mounting section to the lead frame is very poor. Outer leads are formed entirely independently from the electronic component mounting section, and it is accordingly necessary to newly fix the outer leads by means of transfer molding or the like.